Capacitive coupling in hybrid Graphene-GaAs nanostructures

TL;DR

This paper demonstrates a hybrid graphene-GaAs nanostructure where the electronic properties of each component can be tuned via capacitive coupling, enabling potential studies of strong interactions and coherent effects between the materials.

Contribution

It introduces a novel hybrid nanostructure combining graphene and GaAs with tunable electronic coupling and demonstrates its ability to probe localized charges and quantum conductance phenomena.

Findings

Graphene forms Schottky barriers enabling density tuning of the 2DEG.

Quantum point contacts exhibit quantized conductance and the 0.7 anomaly.

GaAs nanostructure can detect nearby charges, confirming strong coupling.

Abstract

Coupled hybrid nanostructures are demonstrated using the combination of lithographically patterned graphene on top of a two-dimensional electron gas (2DEG) buried in a GaAs/AlGaAs heterostructure. The graphene forms Schottky barriers at the surface of the heterostructure and therefore allows tuning the electronic density of the 2DEG. Conversely, the 2DEG potential can tune the graphene Fermi energy. Graphene-defined quantum point contacts in the 2DEG show half-plateaus of quantized conductance in finite bias spectroscopy and display the 0.7 anomaly for a large range of densities in the constriction, testifying to their good electronic properties. Finally, we demonstrate that the GaAs nanostructure can detect charges in the vicinity of the heterostructure's surface. This confirms the strong coupling of the hybrid device: localized states in the graphene ribbon could in principle be probed by the underlying confined channel. The present hybrid graphene/GaAs nanostructures are promising for the investigation of strong interactions and coherent coupling between the two fundamentally different materials.